Among the myriad benefits of cellulose derivatives is the ability to reduce oil uptake of fried foods. However, from a processing viewpoint, this benefit was previously limited by the dry handling and solution forming characteristics of cellulose derivatives. Cellulose derivatives, such as methylcellulose (“MC”) and hydroxypropyl methylcellulose (“HPMC”) are normally sold in solid, dry form, and hence their powder handling and processing properties are extremely important.
For example, a low dust content is desirable for dry MC and HPMC. The ability of the dry MC or HPMC to be poured from a container or receptacle is described as flowability. Flowability is affected by particle shape and size distribution, and resulting bulk density. Bulk density is the mass of powdered solid material per unit of volume occupied. Acceptable flowability generally depends upon relatively high bulk density and relatively low angle of repose. The angle of repose is the maximum angle between the slope of a conical discharged pile of powder and the surface it rests upon, a lower angle representing a more widely spread pile.
Often, it is desirable to put MC or HPMC in solution as part of using it in its various applications. Dissolution is frequently described as a process with two overlapping phenomena, dispersion and hydration. Dispersion refers to spreading of particles or groups of polymer chains throughout the solution. Hydration refers to loosening of the polymer chains and expansion of their hydrodynamic volume (and corresponding viscosity buildup). If dispersion is poor, or if hydration outpaces dispersion, hydrated polymer can swell and isolate relatively dry, non-hydrated polymer from the solution, forming lumps. It has long been a goal in the industry to produce MC or HPMC which is readily dispersible and hydrates quickly in aqueous solutions, more particularly at room temperature. Desirable dispersion and hydration are normally characterized by little to no lump formation and a rapid viscosity build up over time, respectively.
Thus, what is needed is a process for making an MC and/or HPMC that shows desirable dispersion and hydration, yet exhibits good flowability and low dust content. Such cellulose derivatives surprisingly were found to show better oil reduction efficiency and improved batter uniformity.